Krister Svensson

Scanning probe energy loss spectroscopy: Angular resolved measurements on silicon and graphite surfaces

Scanning probbe energy loss spectroscopy: Angular resolved measurements on silicon and graphite surfaces

STM studies of passivated Au nanocrystals immobilised on a passivated Au(111) surface: ordered arrays and single electron tunnelling

STM studies of passivated Au nanocrystals immobilised on a passivated Au(111) surface: ordered arrays and single electron tunneling

Scanning probe energy loss spectroscopy

Abstract This article gives a status report on the new technique of scanning probe energy loss spectroscopy (SPELS), which can be viewed as a hybrid between scanning tunnelling microscopy and electron energy loss spectroscopy. The technique provides local energy loss spectra from solid surfaces (at room temperature) with an expected spatial resolution of 1–10 nm and a current best energy resolution of 0.6 eV. Spectra are presented from the graphite and Si(1xa01xa01)-7×7 surfaces as well as metallic (silver and gold) thin films, which enables the chemical analysis capabilities of the technique to be demonstrated. New and future developments are also discussed, including the demonstration of SPELS with screened tips and the prospects for spectral measurements with energy resolution in the vibrational regime.

Imaging surfaces with reflected electrons from a field emission scanning tunnelling microscope: image contrast mechanisms

Electrons backscattered from a scanning tunnelling microscope operating in the field emission mode have been collected to produce images of a rough Si(111) surface. We have obtained a spatial resolution of about 40 nm in such images. Comparison between backscattered electron images and topographic images reveals that edge enhancement and shadowing are important contrast mechanisms.

Dissociation and desorption of ferrocene on graphite by low energy electron impact

Abstract Ferrocene is an iron-containing organometallic molecule with the potential to be used for fabrication of metallic structures on the nanometre scale. We have used high resolution electron energy loss spectroscopy and scanning tunnelling microscopy to study the influence of low energy electron impact on ferrocene physisorbed on graphite. At electron energies below 10xa0eV we find that the ferrocene molecules are readily desorbed, leaving a clean graphite surface behind. For energies of 20–100xa0eV we find evidence of partial fragmentation of the ferrocene. At higher energies, exceeding 200xa0eV, there is complete disintegration of the molecules, leaving iron-containing nanoclusters in a stable film on the surface. Comparisons are drawn with photon-, thermal- and very high electron-energy induced dissociation and desorption.